The object of the behavioral experiments on subhuman primates is to test the ability of the animal with functionally isolated dorsal columns to detect artificial and natural stimuli applied to nerves of the lower extremities. The animals are trained to press levers to obtain food rewards in response to graded, non-painful stimulation of cutaneous, muscle or mixed nerves. The experimental paradigm, thresholds and record evoked potential data that are correlated with behavior. For years it has been assumed that the dorsal column system of the spinal cord of man and other primates subserves vibratory sensibility, kinesthesis, and fine tactile discrimination. Neurological tests in man are routinely performed to test these functions. Evidence has been developing over the past few years to suggest that the dorsal columns may not subserve some or all of the functions attributed to them. These experiments being conducted at Irvine are intended to clarify the intrinsic sensory functions of this spinal cord pathway.